Braking device



June 16, 1936. c. EWALDSON ET AL 0 BRAKING DEVICE Filed Sept. 15, 1934 w. c. EWALDSO/V INVENTORS 0. y. WATERS fiRfilmL A from/Er Patented June 16, 1936 UNITED STATES PATENT OFFICE em 1 Electric Company,

incorporated, New

York, N. Y., a. corporation of New York Application September 15, 1934, Serial No. 744,108 6 Claims. (01. 188-75) 7 This invention relates to a braking device and more particularly to a braking device for controlling intermittently operative rotary machines such as punch presses. p 7 V Qne widely used form' of punch press has a power shaft driven in continuous rotation by a motor and having a heavy fly wheel thereon. A crank-shaft is arranged to be coupled to and uncoupled from the power-shaft by a clutch actuated by a treadle, lever or other means. A punch is actuated by a pitman driven by the crank-shaft and coacts with a die rigidly supported on the frame of the machine. For some kinds of work a non-repeat mechanism may be provided whose function is to automatically disengage the clutch at the end of one revolution of the crankshaft whether the treadle be released or not.

An object of the present invention is to provide simple,- reliable and adjustable means to obviate backlash in the coupling between the power shaft and the crank-shaft of such machines and to ensure the stopping of the crank-shaft in an accurately predetermined position. v t I ne form in which the invention may beembodied comprises a two part friction brake encircling and floating on the shaft, one part being in continuous contact with the shaft to prevent backlash and means being provided to apply the other part of the brake to the shaft under adjustable pressure. The brake may in some instances be" conveniently arranged to be actuated by the treadle or other device which controls the clutch.

Other objects'an'd characteristic featuresof the 1 invention will appear from the following detailed description of one embodiment thereof taken in connection with the accompanying drawing in which thesame reference numerals are applied to identical parts in the several figures and in .which Fig. 1 is a broken view in side elevation of a. punch press provided with a brake mechanism constructed in accordance with the invention and having the pitman removed for clarity, and

Fig. 2 is a fragmentary View thereof in rear eler vation.

In the embodiment of the invention herein disclosed a punch press of well known construction has a generally c-shaped frame 20 having a horizontal bed 2i to hold a die and a vertical guideway 22 to guide a pitman (not shown). A crank-shaft 23 is journalled horizontally in the upper part of the frame and may be coupled to and uncoupled from a power-shaft (not shown) by means of a clutch device (not shown) actuated by a pull rod 24 pivoted on a lever 25 rigidly attached to t a shaft 26 .journalled in the frame 20. A treadle lever 21 pivoted on the frame has one end of a pull rod 28 pivotally secured thereto, the other end of which is pivotedto the lever 25. A second lever 29 is also'rigidly secured to the shaft 26 and has the lower end of a pull rod 33 pivotally attached thereto. The other end of the pull rod 30 is pivoted to the rear free end of a one arm lever 3 l pivoted on a stub shaft 32 mounted in the frame 26. The lever 3! is provided with an integral or rigidly attached cam block 33 located coaxially with the shaft 32. g

p A pair of semicircular brake shoes 34 and 35, pivotally joined at 36, surrounds the shaft 23 and each is provided with a friction lining 3'! of leather or other appropriate material. Each of the shoes is formed opposite to the pivot 36 with a slotted outwardly extending lug 38 and 39 respectively. A bolt 46 having a laterally extended head 4| has its threaded body 42 located in the slots of the lug 39. The bolt head 4 has a broad lower portion bearing against the un'der side of the lug 38 and a narrower .upperportion located freely in the slot of the lug 38 in position to be in contact with the under face of the cam block 33, the upper face of which is in contact with the lug 39. A compression spring 43 presses at its lower end against the upper face of the lug 3'9 and at its upper end against a washer 44 surrounding the bolt body and held infplace by adjustment nuts 45 on the threaded body of the bolt. v v t A supporting member 46 is secured tothe frame and extends out therefrom under the shoe 35 and is formed with a vertically oriented aperture across which extends a square cross-sectioned guide 41 pivotally mounted in the member 46. The shoe 3 is provided with a pair of downwardly extending guide lugs 48 which embrace and slide with a small degree of looseness on the guide 41'. A compfessi'on spring 49 is positioned between the lugs 48 and bears at its upper end against the shoe 35 and at its lower end against the head of an adjustment screw 50 mounted in the guide 41.

The lower shoe 35 is held at all times in contact with the shaft 23 under an unvarying adjustable pressure caused by the spring 49 and floats on the shaft, being supported only by the spring 49 and guided by the lugs 48 coacting with the guide 41. The pressure of this shoe is regulable by means of the screw 50 and tends to keep the crank-shaft dragging against the drive-shaft at all times to obviate any backlash between the crank-shaft and its drive.

When the lever 3| is in the position shown in full lines, i. e. when the operating treadle 21 is held down, the cam block 33 is turned to force the lug 39 up and the bolt head 4| down. This lifts the upper shoe 34 from the shaft without affecting either the lower shoe 35 or the pressure exerted thereon by the spring 49, since the bolt head is free to move in the slotted lug 38. When the treadle is released, the spring 5| forces the lever 3| into the position shown in dotted lines, and the cam block 33 is rotated clockwise allowing the upper brake shoe 34 to move down and press on the shaft 23 under the pressure of the spring 43. Since the bolt head 4| now pulls up against the under side of the lug 38 the pressure of the spring 43 also acts in this position to press the lower brake shoe 35 against the shaft.

The apparatus disclosed above is thought of as a repeating press, i. e. one in which the crankshaft 23 keeps on revolving as long as the treadle 21 is held down. When the treadle is released and moves up, the machine is so constructed that the clutch remains engaged until the offset part of the crank has passed its lowest position and is moving up. The springs 49 and 43 are so adjusted that the momentum of the crank-shaft and its associated parts tending to continue the revolution of the crank-shaft will be dissipated by the brake as the crank reaches the top of its orbit.

If the press be provided with a non-repeat device, the clutch is engaged and'the crank-shaft set in motion, by depressing the treadle which action also lifts the upper brake shoe out of engagement with the shaft. In this case, however, the non-repeat mechanism which automatically disengages the clutch as the crank moves up, is

arranged to also automatically release the lever 3| to move from the full line position to the dotted line position thus allowing the spring 43 to move the upper shoe down against the shaft.

The embodiment of the invention herein disclosed is merely illustrative and may be modified and departed from in many ways without departing from the spirit and scope of the invention as pointed out in and limited only by the appended claims.

What is claimed is:

1. A braking device to act on a rotary member comprising a first brake shoe mounted to float on the rotary member in continuous contact therewith, first pressure exerting means to press the shoe against the member under constant pressure, a second brake shoe movably mounted with respect to the member, and second pressure exerting means to apply the second shoe to the member and to exert pressure of both shoes on the member, the second pressure exerting means being independent of the first pressure exerting means.

2. A braking device to act on a rotary member comprising a first brake shoe mounted to float on the rotary member in continuous contact therewith, adjustable first pressure exerting means to press the shoe against the member under constant pressure, a second brake shoe movably mounted with respect to the member, and adjustable second pressure exerting means to apply the second shoe to the member and to exert pressure of both shoes on the member, the second pressure exerting means being independent of the first pressure exerting means.

3. A braking device to act on a rotary member comprising a pair of brake shoes, one of the brake shoes being mounted to float on the rotary member in continuous contact therewith, first pressure exerting means to press the floating shoe against the member under constant pressure, means to apply the second shoe to the member and to disengage it therefrom, and second pressure exerting means to exert pressure of both shoes on the member when the second shoe is applied thereto, the second pressure exerting means being independent of the first pressure exerting means.

4. A braking device to act on a rotary member comprising a pair of brake shoes, one of the brake shoes being mounted to float on the rotary member in continuous contact therewith, adjustable first pressure exerting means to press the floating shoe against the member under constant pressure, means to apply the second shoe to the member and to disengage it therefrom, and adjustable second pressure exerting means to exert pressure of both shoes on the member when the second shoe is applied thereto, the second pres- 3 sure exerting means being independent of the first pressure exerting means.

5. A braking device to act on a rotary member comprising a pair of semi-circular brake shoes pivoted together and encircling the member, first pressure exerting means to keep one of the shoes in continuous contact with the member, means actuable to engage the other shoe with the member, and second pressure exerting means to exert pressure of both shoes on the member.

6. A braking device to act on a rotary member comprising a pair of semi-circular brake shoes pivoted together and encircling the member, first spring means to maintain one of the shoes in continuous contact with the member and to exert continuous pressure of the said shoe on the member, second spring means tending to engage the other shoe with the member and to exert pressure thereof against the member and to exert additional pressure of the first shoe against the member, and means actuable to disengage the second shoe from the member and to release the additional pressure of the first shoe.

WALDEMAR. C. EWALDSON. DANIEL V. WATERS. 

